Portable devices are rapidly evolving into multi-function devices, which incorporate computing, communication, and entertainment functions in one device. Tactile feedback is increasingly incorporated into these portable devices, such as mobile phones, personal digital assistants, and other devices. Historically, however, portable devices have only featured basic vibration functionality. For example, mobile phones may only have the ability to pulse a vibration actuator on and off at a single amplitude.
These mobile phones and other haptic devices may drive a standard audio signal through a Multi-Function Transducer (MFT), to produce vibration. Some such devices may rely on existing frequencies of the audio signal to randomly drive vibration in the MFT, rather than using a specific vibration control signal. If such frequencies are not found in the audio signal, no vibration is produced.
While some vibration capability currently exists, developments in portable device technology and user demands are driving a need for advanced vibration capabilities in mobile phones. And manufacturers of these devices may seek various ways to employ such advanced vibration capabilities to their portable devices for enhanced functionality and control.
At the same time that demand for vibration feedback is growing, the number of different haptic devices that support vibration feedback is growing. The growing variety of different haptic devices creates a dilemma for device designers. On the one hand, a device designer may devote time and resources to tailoring vibrotactile feedback to the specific capabilities of different devices. Alternatively, a device designer may choose to provide the same generic vibrotactile feedback signal to many different devices, and accept that the generic signal may fail to take advantage of the enhanced functionality of any specific haptic device.